1. Field of the Invention
The present invention relates to a starting device for motor vehicles that is provided with a friction element arranged between an engine and wheels and capable of producing creep torque by slipping the friction element.
2. Description of the Related Art
A starting device for motor vehicles of this kind is disclosed in Japanese patent laying-open publication No. 2001-116067. This starting device is arranged between an engine and a transmission and decreases clutch torque when a motor vehicle is stopped by braking operation. By reducing the clutch torque at two stages, the starting device produces strong creep torque for creep of the vehicle for a predetermined period in preparation for a quick response to restart for a short time from vehicle stop, and after the period produces weak creep torque so as to protect a clutch from deterioration in its durability and save fuel.
The above known conventional starting device, however, encounters a problem that the creep torque can not satisfy fuel saving, clutch durability, and a restart response at a time, because the predetermined period for producing the creep torque is fixed. Specifically, it produces the creep torque for the predetermined fixed period in a case where a driver wants no creep of the vehicle, causing deterioration in clutch durability and fuel economy, and after the predetermined time, it can not produce the creep torque for moving the vehicle although the driver wants creep of the vehicle, causing degradation in response time for restarting the vehicle.
It is, therefore, an object of the present invention to provide a starting device for motor vehicles which overcomes the foregoing drawbacks and can produce creep torque to meet a driver's demand for creep of a motor vehicle.